There are the conventionally-developed X-ray radiation sources configured in the configuration wherein an X-ray tube, a high-voltage generation module, and others are incorporated in a housing having an X-ray radiation window. For example, in the industrial X-ray generation device described in Patent Literature 1, the high voltage side of a boost circuit and the cathode of the X-ray tube are arranged close to each other. For example, in the soft X-ray generation device described in Patent Literature 2, a thin film comprised of diamond grains with predetermined grain sizes is provided on the surface of an emitter. This device has the configuration wherein the whole housing of the X-ray tube is made of aluminum and wherein a metal member is located outside the surface where the cathode of the X-ray tube is arranged.
In the X-ray radiation sources as described above, it is conceivable to use alkali-containing glass, e.g., such as soda lime glass for a bottom plate of the housing or the like, from the viewpoint of matching the coefficient of thermal expansion thereof with that of power-supply terminals of the X-ray tube. Since the coefficient of thermal expansion of such glass is close to those of various electrodes and sealing materials arranged in the X-ray tube, it becomes feasible to form a vacuum housing with high vacuum maintaining performance.